1. Technical Field
The present invention relates to a tire condition acquisition device and tire condition monitoring system that can avoid malfunction and function loss due to a tire puncture repair agent.
2. Related Art
Conventionally, tire air pressure inspection management for vehicles has been important, and many accidents are caused by improper tire pressure. Therefore, tire condition monitoring systems are known that include a tire information acquisition device in each wheel that detects and transmits information regarding an air pressure in a wheel tire, and a monitoring device that acquires the tire air pressure information transmitted from the tire information acquisition devices in each tire, monitors the air pressure for each tire, and issues a warning when there is a problem with the air pressure (for example, see Japanese Patent No. 3962073).
The tire information acquisition device of this tire condition monitoring system is disposed in an internal space formed between a tire and a wheel. The tire information acquisition device is constructed from an air pressure sensor formed from a pressure detecting element that detects air pressure inside the tire and a transmitter or the like that converts detection results of the air pressure sensor to an electric signal and transmits the electric signal to a monitoring device via electromagnetic waves, the tire information acquisition device being stored in a case. The case is provided with a ventilation hole in order to introduce air from the internal space formed between the tire and the wheel into the air pressure sensor located therein. The monitoring device is disposed in proximity to a driver's seat, receives tire air pressure information transmitted from the tire information acquisition device, and if the air pressure of the tire is below a standard pressure set beforehand, a predetermined warning is generated for the driver.
However, if the tire equipped with the tire information acquisition device is punctured and the tire is repaired using a tire puncture repair agent, there is a problem that the tire information acquisition device will cease functioning due to the tire puncture repair agent. Specifically, if the tire puncture repair agent adheres to the ventilation hole of the tire information acquisition device, communication between the tire inner space and the air pressure sensor will be blocked, thereby making detection of the air pressure impossible.
In order to resolve the aforementioned problems, a tire air pressure monitoring system, described in Japanese Unexamined Patent Application Publication No. 2007-196834, a wheel condition detecting device, described in Japanese Unexamined Patent Application Publication No. 2008-062730, and the like have been proposed.
With the tire air pressure monitoring system described in Japanese Unexamined Patent Application Publication No. 2007-196834, if a tire puncture repair agent is used to repair a puncture, after the puncture is repaired occupants are notified that there is a possibility that a tire air pressure will decrease. Specifically, puncture determining means that determine if each tire of a vehicle has been punctured, and tire puncture repair agent use determining means that determine after a puncture has been determined whether or not the puncture has been repaired using the tire puncture repair agent are provided. This system is configured so as to issue a warning even if a tire air pressure value transmitted from the air pressure sensor is a normal value when the tire puncture repair agent use determining means determines that the puncture has been repaired using the tire puncture repair agent.
Furthermore, with the wheel condition detecting device described in Japanese Unexamined Patent Application Publication No. 2008-062730, a connecting part opening and closing mechanism that opens and closes a ventilation hole formed in a case is provided on a TPMS valve, thereby restricting a tire puncture repair agent from entering a detection space through the ventilation hole when a puncture is repaired. This connecting part opening and closing mechanism is configured so as to include a mechanical mechanism containing a lid body and a screw coil spring, and the ventilation hole is automatically opened and closed by centrifugal force that acts on a wheel. Thereby, foreign material can be prevented from entering from a connecting part for detection, and normal detection conditions can be maintained.
However, with the tire air pressure monitoring system described in Japanese Unexamined Patent Application Publication No. 2007-196834, puncture determining means and tire puncture repair agent use determining means are required, resulting in a complex construction, and increased manufacturing costs. Additionally, since a warning is issued after repairs are made using the tire puncture repair agent, even if the tire air pressure value is at a normal value, there is a problem that a driver will have difficulty determining whether or not the tire air pressure is normal.
Furthermore, with the wheel condition detecting device described in Japanese Unexamined Patent Application Publication No. 2008-062730, the connecting part opening and closing mechanism is complicated. Therefore, there are problems of complicated manufacturing and additional costs.
An object of the present invention is to provide a tire condition acquisition device and tire condition monitoring system that can reduce malfunction and loss of function of the tire condition acquisition device even if a puncture is repaired using a tire puncture repair agent.